1. Field of the Invention
The present invention relates to a noise prediction system for estimating or predicting the noise signal contained in a data signal such as a voice signal.
2. Description of the Prior Art
Conventionally, there have been developed techniques capable of predicting the noise signal contained in a data signal, such as in a voice signal, and removing the same so as to obtain a voice signal of an excellent quality. The important point in these techniques is an prediction method for predicting the noise signal contained in the data signal.
For example, there is known a method for analyzing the voice signal containing a white noise signal by a Fourier transformation. The white noise signal is continuously present, whereas the voice signal is present intermittently. The white noise signal is detected during the absence of the voice signal, and the noise signal data is obtained immediately before the leading edge of the voice signal, and the noise signal data is stored and is used for counterbalancing the white noise signal present during the presence of the voice signal. According to this method, the noise prediction for the noise signal contained in the data portion is effected based on the noise information immediately before the voice signal portion.
However, according to this prediction method, since the noise signal data immediately before the voice signal is used, the prediction of the noise signal in the voice signal areas is likely to be coarse and inaccurate.